1. Field of the Invention
The present invention relates a liquid crystal display (LCD) device, and more particularly, to an LCD device with enhanced picture quality achieved by preventing seal pattern spots (blurs) due to a slide preventing adhesive on a substrate applied during an attaching process.
2. Description of the Related Art
Recently, as various mobile electronic devices including mobile phones, personal digital assistants (PDAs), and notebook computers are being developed, demands for a light, thin, short, and small flat panel display device are increasing. As a result, research and development for flat panel display devices, such as LCDs (liquid crystal displays), PDPs (plasma display panel), FEDs (field emission display), and VFD (vacuum fluorescent displays) are actively ongoing. Of these displays, the LCD is the one of most interest because of its implementation of mass-production techniques, ease in driving, and high picture quality.
FIG. 1 is a schematic sectional view of a general LCD. As shown, the general LCD device includes a lower substrate 5, an upper substrate 3, and a liquid crystal layer 7 formed between the lower and upper substrates 5 and 3. The lower substrate 5 is a driving device array substrate. Though not shown, a plurality of pixels is formed on the lower substrate 5 and each pixel includes a driving device, such as a thin film transistor (TFT). The upper substrate 3 is a color filter substrate and includes a color filter layer for implementing actual colors. A pixel electrode and a common electrode are formed on the lower and upper substrates 5 and 3, respectively, and an alignment film for aligning liquid crystal molecules of the liquid crystal layer 7 is coated thereon.
The lower and upper substrates 5 and 3 are attached by a seal pattern (seal material) 9 and the liquid crystal layer 7 is formed between the seal patterns. Information is displayed by controlling the amount of light transmitted through the liquid crystal layer by driving liquid crystal molecules using the driving device formed on the lower substrate 5.
The process of fabricating the LCD device can be divided into a driving device array substrate process for forming the driving device on the lower substrate 5, a color filter substrate process for forming color filters on the upper substrate 3, and a cell process. The processes of fabricating the LCD device will now be described with reference to FIG. 2.
First, in the driving device array substrate process, a plurality of gate lines and data lines are arranged to define pixel regions on the lower substrate 5, and a TFT, namely, the driving device, connected with the gate line and the data line is formed at each pixel region (step S101). In addition, a pixel electrode is formed connected with the TFT to drive the liquid crystal layer according to a signal applied thereto through the TFT. In the color filter substrate process, R, G, and B (red, green, and blue) color filter layers for implementing color and the common electrode are formed on the upper substrate 3 (step S104).
Subsequently, an alignment film is formed on the upper and lower substrates 5 and 3, respectively, and rubbed to provide an alignment control force or a surface fixing force (namely, a pre-tilt angle and an alignment direction) to liquid crystal molecules of the liquid crystal layer formed between the upper and lower substrate 5 and 3 (steps S102 and S105). Thereafter, spacers for uniformly maintaining a cell gap are spread on the lower substrate 5, a seal pattern is coated at an outer edge of the upper substrate 3, and then, the lower and upper substrates 5 and 3 are attached to each other by applying a certain pressure thereto (steps S103, S106 and S107).
The upper and lower substrates 5 and 3 are formed from a large-size glass substrate. Specifically, a plurality of panel regions are formed on a large-scale glass substrate and the TFT, namely, the driving device, and the color filter layer are formed at each panel region. To fabricate each liquid crystal panel, the glass substrates are cut and processed (step S108). Then, liquid crystal is injected into each processed liquid crystal panel through a liquid crystal injection opening, and the liquid crystal injection opening is sealed to form a liquid crystal layer (step S109). Thereafter, each liquid crystal panel is tested to complete the fabrication of the LCD device (step S110).
The attaching process is performed by the seal pattern formed on the upper substrate, and in this case, an adhesive for preventing sliding of the upper substrate is formed at an outer edge of the lower substrate. Namely, as shown in FIG. 3, a slide preventing adhesive 11 is formed at the outer edge of the lower substrate 5 and prevents the upper substrate 3 from sliding with respect to the lower substrate 5 so that the attached alignment between the upper substrate 3 and the lower substrate 5 is not be distorted.
The adhesive 11 is dropped onto the lower substrate 5 in a dot form, and when the upper substrate 3 is pressed to be attached with the lower substrate, the adhesive 11 is pressed by the upper substrate 3. At this time, the adhesive 11 spreads out to the region of the seal pattern 9, and in this case, after the attaching, the seal pattern 9 is separated along the region intruded by the adhesive 11. Because of the separation of the seal pattern 9 caused by the adhesive 11, spots are generated due to a defective gap of the seal pattern 9, thereby degrading a picture quality.